Variety reports that Big Eyes will deal with Keane's personal life, specifically her lawsuit against her second husband, Walter Keane, who had taken credit for her mass-produced artwork until the 1960s. Not to give away spoilers, but according to Keane's Wikipedia page, she finally won the rights to her work in divorce proceedings that went all the way to Federal court. How did she prove she was the real talent? She painted in court in front of the judge (Walter meanwhile declined to do the same). I apologize for ruining the ending of the film, but I figured I'd share that info so that when the scene pops up in Big Eyes, you'll know it isn't just some cinematic tool used to make the story more visually interesting.
Regardless of how the movie is received now, though, it's sure to be one of the most popular movies come 2173 (see Woody Allen's Sleeper, which claims that in the future Keane is considered one of the greatest artists of all time)